1. Field of the Invention
This invention relates to a system for monitoring the progress of a plurality of batches of semiconductor wafers or memory disks through a multiplicity of processing operations at various locations within and between plant facilities. It also relates to process carriers for use in such a system, such as the Method and Apparatus for Monitoring the Location of Wafer Disks disclosed and described in co-pending application Ser. No. 07/061,935, filed June 11, 1987, now U.S. Pat. No. 4,827,110, issued May 2, 1989.
2. Description of Related Information
In the semiconductor manufacturing industry, semiconductor wafers are moved through a manufacturing plant to a number of different locations where they are etched, cleaned, processed using photolithography operations, tested and subjected to various other manufacturing, testing and processing operations. Similarly, memory disks are also moved in process carriers through a sequence of manufacturing operations in and between various manufacturing facilities.
It is common in the industry to handle wafers or memory disks in batches within carriers specifically designed for the purpose of supporting the wafers or memory disks in the proper position for the manufacturing and processing machinery, which may either process the disks or wafers while they remain in the carriers or remove them for a processing operation and then return them to the carrier. A batch is defined and used hereinafter to mean one or more (up to the capacity of the carrier) of the semiconductor wafers or memory disks.
In a manufacturing plant, it is desirable to track the progress of a batch of wafers or memory disks through the manufacturing process. Heretofore, this has been done on a manual basis, either by generating paper records to track the progress of particular batches through the various manufacturing and processing operations or by some semi-automated system such as manual keyboard entry.
Although methods of identifying objects using radio frequency interrogation of transponder ttag structures have existed for the past twenty years, the application of those techniques to monitoring the progress of batches of semiconductor wafers or memory disks through processing and manufacturing operations has only recently been successfully developed, as described in our earlier filed co-pending application Ser. No. 07/061,935, filed June 11, 1987. The present application describes process carriers having an transponder tag attached thereto for use in such a tracking and identification system. The transponder tag may be directly affixed to the surface of the carrier, preferably under a protective cover, or the tag may be encapsulated in a protective capsule and the capsule attached to the surface of the carrier, preferably in a removable manner. The attachment of the transponder tag to the carrier is designed to protect the transponder tag from the deleterious effects of exposure to rigorous processing chemicals. This invention also provides a separate encapsulated transponder tag in such a protective capsule, so that existing carriers may be modified or retrofitted with the separate encapsulated transponder tag for use in the present location monitoring system.